The magnetic disk and head are key components of magnetic disk drives. When the disk drive is in operation, the magnetic disk rotates at speed, and the magnetic head slider is positioned a small distance above the magnetic disk due to the well known “air bearing” effect.
The distance between the slider and the surface of the magnetic disk (“head-disk spacing”) is a critical parameter relating to the recording density and reliability of the disk drive. A reduction in the head-disk spacing can be used to achieve an increase in recording density.
In the currently existing drives, the head-disk spacing is around 15 to 30 nanometers (nm). It is expected that head-disk spacing will fall far below 10 nm levels in due course. Accordingly, the measurement of slider position relative to the surface of a magnetic disk is becoming increasingly important for achieving design targets while ensuring product quality.
At present, optical techniques exist to test the flying height of a magnetic head slider before its installation in a magnetic drive. These techniques are generally recognised as unsatisfactory as the accuracy and data repeatability in measurement become more critical when technology moves to deep sub-10 nm head disk spacing. Furthermore, the three dimensional stability of a slider's position and orientation is becoming crucially important in sub-10 nm spaced head-disk systems, and the currently existing optical techniques cannot provide a direct measurement of the stability.
Accordingly, it is an object of the invention to address these and other problems associated with existing techniques by providing an improved method for measurement of the spatial position and orientation of a recording head slider with respect to an adjacent disk surface.